1. Field of the Invention
The invention relates to a structure of a surface discharge scheme AC type plasma display panel, and a method of manufacturing the same.
2. Description of the Related Art
Recent years, a plasma display panel of a surface discharge scheme AC type as an oversize and slim display for color screen has been received attention, which is becoming widely available.
FIG. 27 is a schematically front view illustrating a cell structure of a conventional surface discharge scheme AC type plasma display panel. FIG. 28 is a sectional view taken along the Vxe2x80x94V line of FIG. 27. FIG. 29 is a sectional view taken along the Wxe2x80x94W line of FIG. 27.
In FIGS. 27 to 29, on the backside of a front glass substrate 1 to serve as a display surface of the plasma display panel, there is sequentially provided with a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2); a dielectric layer 2 overlaying the row electrode pairs (Xxe2x80x2, Yxe2x80x2); and a protective layer 3 made of MgO which overlays a backside of the dielectric layer 2.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are respectively comprised of wider transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 each of which is formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xbxe2x80x2 and Ybxe2x80x2 each of which is formed of a metal film complementary to conductivity of the transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged opposing each other with a discharge gap gxe2x80x2 in between, and alternate in the column direction such that each row electrode pair (Xxe2x80x2, Yxe2x80x2) forms a display line (row) L on a matrix display.
A back glass substrate 4 faces the front glass substrate 1 with a discharge space Sxe2x80x2, filled with a discharge gas, in between. The back glass substrate 4 is provided with a plurality of column electrodes Dxe2x80x2 arranged to extend in a direction perpendicular to the row electrode pairs Xxe2x80x2 and Yxe2x80x2; band-shaped partition walls 5 each extending between the adjacent column electrodes Dxe2x80x2 in parallel; and a phosphor layer 6 consisting of a red phosphor layer 6(R), green phosphor layer 6(G) and blue phosphor layer 6(B) which respectively overlay side faces of the partition walls 5 and the column electrodes Dxe2x80x2.
In each display line L, the partition wall 5 defines discharge cells Cxe2x80x2, each forming a unit light emitting area, at respective areas of the discharge space Sxe2x80x2 in which the column electrode Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2) intersect.
In the above surface discharge scheme AC type plasma display panel, an image is displayed as follows:
First, through addressing operation, opposite discharge is caused selectively between the row electrode pairs (Xxe2x80x2, Yxe2x80x2) and the column electrodes Dxe2x80x2 in the respective discharge cells Cxe2x80x2, to scatter lighted cells (the discharge cell in which wall charge is formed on the dielectric layer 2) and nonlighted cells (the discharge cell in which wall charge is not formed on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the addressing operation, in all the display lines L, discharge sustain pulses are applied alternately to the row electrode pairs (Xxe2x80x2, Yxe2x80x2) in unison, and thus surface discharge is produced in the lighted cells on every application of the discharge sustain pulse.
In this manner, the surface discharge in each lighted cell generates ultraviolet radiation, and thus the red phosphor layer 6(R) and/or the green phosphor layer 6(G) and/or the blue phosphor layer 6(B) each formed in the discharge cell Cxe2x80x2 are excited to emit light, resulting in forming the display image.
Such a conventional surface discharge scheme AC type plasma display panel has a disadvantage in which contrast on a screen formed on the plasma display panel is decreased, because of that, in each area between the back-to-back bus electrodes Xbxe2x80x2 and Ybxe2x80x2 serving as a non-display line, incoming ambient light is reflected off by the phosphor layer 6 formed on the back glass substrate 4.
Hence, the applicant of the present invention has suggested an alternative plasma display panel capable of improving contrast. The improvement of contrast is accomplished by forming a black or dark-brown band-shaped light-shield layer 7 extending along the row direction between bus electrodes Xbxe2x80x2 and Ybxe2x80x2 arranged back to back on a dielectric layer 2 so as to prevent the reflection of ambient light from the non-display lines.
However, the light-shield layer 7 formed by a printing technique has a disadvantage on the pattern precision and has not yet completely prevented the reflection of the ambient light.
Therefore, the further improvement of contrast has been desired.
The present invention has been made to solve such a conventional disadvantage in the surface discharge scheme AC type plasma display panel.
It is therefore a first object of the present invention to provide a plasma display panel which is capable of further improving contrast on a screen formed on the plasma display panel to display high quality images.
Further, it is a second object of the present invention to provide a method of manufacturing a plasma display panel capable of further improving contrast on a screen formed on the plasma display panel to display high quality images.
To attain the above first object, a plasma display panel according to a first invention includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to form display lines on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction to constitute unit light emitting areas at respective positions corresponding to the intersections of the column electrodes and the row electrode pairs in a discharge space on a surface of a back substrate facing the front substrate with a discharge space in between, in which each row electrode of the row electrode pair is made up of transparent electrodes, each formed opposite to the corresponding transparent electrode via a predetermined discharge gap, and a bus electrode which extends in the row direction and is connected ends of the transparent electrodes situated opposite to the discharge gap. Such plasma display panel features in that a light-shield layer is formed at least on a portion between the two back-to-back bus electrodes of the adjacent row electrode pairs in the row direction and on required portions in proximity to the sides of the bus electrodes each connected to the transparent electrode, on the backside of the front substrate.
The plasma display panel according to the first invention is designed to form the display images by means of the opposing discharge selectively caused between the transparent electrode of each row electrode and the corresponding column electrode and the surface discharge caused between the transparent electrodes through the discharge gap in each row electrode pair. The light-shield layer which is black, dark brown or the like in color absorbing light overlays each portion between the two back-to-back bus electrodes which serves as a non-display line during the formation of images, and each required portion of the proximal ends of the transparent electrodes. At these proximal ends, the discharge light emission is low due to the increased distance from the discharge gap in which the surface discharge is caused.
In consequence, according to the first invention, the light-shield layer absorbs ambient light incident from the display surface of the front substrate directed toward the non-display area for images not to permit the reflection of ambient light. This improves the contrast on the screen. Further, the light-shield layer is also formed on the required portion in proximity to the connection of the bus electrode to the transparent electrodes so as to overlay the portions not much contributing to the light emission for forming images. For this reason, it is possible to sufficiently prevent the reflection of ambient light in the non-displaying image area even when the precision of formation of the light-shield layer is not high, and this further improves the contrast on the screen.
To attain the aforementioned first object, the plasma display panel according to a second invention features, in addition to the configuration of the first invention, in that a partition wall is arranged between the front substrate and the back substrate and includes vertical walls extending in the column direction and transverse walls extending in the row direction to define the discharge space into the unit light emitting areas in the row direction and the column direction, and in that the light-shield layer is formed at a position corresponding to a face of the transverse wall of the partition wall on the front substrate side when viewed from the front substrate.
According to the plasma display panel of the second invention, the light-shield layer overlays the portions of the display surface of the front substrate which serve as the non-display image area because the portions oppose the transverse walls of the partition wall defining the discharge space into the unit light emitting areas. Therefore, it is possible to improve the contrast on the screen even when the discharge space is defined by the partition wall having the transverse walls.
To attain the aforementioned first object, the plasma display panel according to a third invention features, in addition to the configuration of the first invention, in that a portion of the bus electrode on the front substrate side consists of a light absorption layer.
According to the plasma display panel of the third invention, there are the light absorption layer forming the portion of each bus electrode on the front substrate side and the light-shield layer formed on each portion between the two back-to-back bus electrodes and each required portion in proximity to the connections of the bus electrodes to the transparent electrodes. These two layers overlay most of portions serving as the non-display image area on the display surface of the front substrate to prevent the reflection of ambient light from such portions, resulting in improvement in contrast on the screen.
To attain the aforementioned first object, the plasma display panel according to a fourth invention features, in addition to the configuration of the first invention, in that the light-shield layer is formed on a portion of the backside of the front substrate opposing the vertical wall of the partition wall.
According to the plasma display panel of the fourth invention, the light-shield layer overlays the portions on the display surface of the front substrate which serve as the non-display image area because they oppose the transverse walls of the partition wall defining the discharge space into the unit light emitting areas. Therefore, it is possible to improve the contrast on the screen even when the discharge space is defined by the partition wall having the vertical walls.
To attain the aforementioned first object, the plasma display panel according to a fifth invention includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to respectively form display lines and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction to constitute unit light emitting areas in a discharge space at respective positions, corresponding to intersections of the column electrodes and the row electrode pairs, on a surface of a back substrate facing the front substrate with a discharge space in between, each row electrode of the row electrode pair being made up of transparent electrodes each formed to oppose the corresponding transparent electrode via a predetermined discharge gap, and a bus electrode extending in the row direction and connected an end of the transparent electrode situated opposite to the discharge gap. Such plasma display panel features in that a light-shield layer is formed on the dielectric layer to overlay a portion situated between the row electrode pairs and surrounded by the respective bus electrodes when viewed from the front substrate.
The plasma display panel according to the fifth invention is designed to form the display images by means of the opposing discharge selectively caused between the transparent electrode of each row electrode and the corresponding column electrode and the surface discharge caused between the transparent electrodes through the discharge gap in each row electrode pair. The light-shield layer being black, dark brown or the like in color absorbing light overlays each portion of the dielectric layer opposing the portion between the two back-to-back bus electrodes which serves as a non-display line during the formation of images.
Hence, according to the fifth invention, the light-shield layer absorbs ambient light incident from the display surface of the front substrate directed toward the non-display image area not to permit the reflection of ambient light. This improves the contrast on the screen. Further, since the light-shield layer is also formed on the dielectric layer, the precision of the patterning can be increased when the light-shield layer is formed. This further improves the contrast on the screen.
To attain the aforementioned first object, the plasma display panel according to a sixth invention features, in addition to the configuration of the fifth invention, in that a partition wall is arranged between the front substrate and the back substrate and includes vertical walls extending in the column direction and transverse walls extending in the row direction to define the discharge space into the unit light emitting areas in the row direction and the column direction, and in that the light-shield layer is formed on the dielectric layer in alignment with the vertical wall of the partition wall when viewed from the front substrate.
According to the plasma display panel of the sixth invention, although the vertical walls serves as non-display lines in the case where the partition wall including the vertical walls and the transverse walls defines the discharge space into the pattern in which parallel lines cross at right angles, the reflection of ambient light incident upon the vertical walls is prevented by the light-shield layer formed on the portion of the dielectric layer opposing the vertical wall. This further improves the contrast on the screen.
To attain the aforementioned first object, the plasma display panel according to a seventh invention features includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to respectively form display lines and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction to constitute unit light emitting areas in a discharge space at respective positions, corresponding to intersections of the column electrodes and the row electrode pairs, on a surface of a back substrate facing the front substrate with a discharge space in between, each row electrode of the row electrode pair being made up of transparent electrodes each formed to oppose the corresponding transparent electrode via a predetermined discharge gap, and a bus electrode extending in the row direction and connected an end of the transparent electrode situated opposite to the discharge gap. Such plasma display panel features in that an additional portion is formed on a backside of the dielectric layer to oppose the back-to-back arranged bus electrodes of the adjacent row electrode pairs in the column direction and a portion surrounded by the back-to-back bus electrodes and to protrude toward the discharge space, and in that a light-shield layer is formed on at least a portion of the additional portion opposing the portion surrounded by the back-to-back bus electrodes.
The plasma display panel according to the seventh invention is designed to form the display images by means of the opposing discharge selectively caused between the transparent electrode of each row electrode and the corresponding column electrode and the surface discharge caused between the transparent electrodes through the discharge gap in each row electrode pair. The light-shield layer being black, dark brown or the like in color absorbing light overlays each portion of the additional portion opposing the area between the two back-to-back bus electrodes which serves as a non-display line during the formation of images.
Hence, according to the seventh invention, the light-shield layer configured in the additional portion absorbs ambient light incident from the display surface of the front substrate directed toward the non-display image area not to permit the reflection of ambient light. This improves the contrast on the screen. Further, since the light-shield layer is also formed on the additional portion, the precision of patterning can be increased when the light-shield layer is formed. This further improves the contrast on the screen.
To attain the aforementioned first object, the plasma display panel according to an eighth invention features, in addition to the configuration of the seventh invention, in that the additional portion is formed of a black or dark color photosensitive resin.
According to the plasma display panel of the eighth invention, the entire additional portion serves as a light-shield layer. This can almost completely prevent the reflection of ambient light incident upon the non-display area between the bus electrodes so as to improve the contrast.
To attain the aforementioned first object, the plasma display panel according to a ninth invention features, in addition to the configuration of the seventh invention, in that a joint face of the additional portion to the dielectric layer consists of the light-shield layer.
According to the plasma display panel of the ninth invention, the light-shield layer formed on the joint face of the additional portion to the dielectric layer prevents the reflection of the ambient light incident upon the non-display line area between the bus electrodes, resulting in the improvement in contrast.
To attain the aforementioned first object, the plasma display panel according to a tenth invention features, in addition to the configuration of the seventh invention, in that a partition wall is arranged between the front substrate and the back substrate and includes vertical walls extending in the column direction and transverse walls extending in the row direction to define the discharge space into the unit light emitting areas in the row direction and the column direction, and in that the light-shield layer forms a face of the partition wall on the front substrate side.
According to the plasma display panel of the tenth invention, although the portions of the vertical walls of the partition wall serves as the non-display image area in the case where the partition wall including the vertical walls defines the discharge space into the unit light emitting areas, since the light-shield layer forms the face of the vertical wall on the display surface side, the reflection of the ambient light incident upon the non-display image area is prevented, resulting in the further improvement in contrast on the screen.
To attain the aforementioned second object, a method of manufacturing a plasma display panel according to an eleventh invention features the steps of a lamination process for laminating a film including a black or dark color photosensitive resin layer on a front substrate on which row electrodes each including transparent electrodes and a bus electrode are formed in pair to extend in a row direction and be arranged in a column direction, with the photosensitive resin layer facing the front substrate to overlay the row electrode pairs; and a removal process for removing the photosensitive resin layer except for the portions corresponding to at least a portion between the bus electrodes of the two row electrodes situated back to back and a required portion in proximity to the connection of the bus electrode with the transparent electrodes, after the lamination process.
According to the method of manufacturing the plasma display panel of the eleventh invention, after the film including the black or dark color photosensitive resin layer is laminated on approximately the front of the front substrate on which the row electrode pairs are formed, a light-shield layer is formed to overlay the portions serving as the non-display image area by the technique for removing the photosensitive resin layer except for the portion corresponding to the non-display image area. Therefore, the light-shield layer can be formed with high precision.
To attain the aforementioned second object, the method of manufacturing the plasma display panel according to a twelfth invention features, in addition to the configuration of the eleventh invention, in that the film consists of two layers of the black or dark color photosensitive resin layer and a non-photosensitive resin layer, and has a thickness larger than that of the transparent electrode of the row electrode, and the photosensitive resin layer has a thickness equal to or smaller than that of the transparent electrode.
When the film is laminated on the front substrate on which the dumps are formed due to the bus electrodes and the like, if a thickness of the film is equal to or smaller than that of the dump, a problem in which air is caught up in the dump area occurs.
According to the method of manufacturing the plasma display panel of the twelfth invention, however, while a film thickness of the photosensitive resin layer is set to be smaller than that of the bus electrode, the non-photosensitive resin layer functioning as a dummy layer can increase the total film thickness of the film so as to allow it to sufficiently exceed the film thickness of the bus electrode. For this reason, catching up air in the dump area is prevented.
To attain the aforementioned second object, the method of manufacturing the plasma display panel according to a thirteenth invention features, in addition to the configuration of the eleventh invention, in that the photosensitive resin layer is removed by the patterning using an exposure mask in the removing process.
According to the method of manufacturing the plasma display panel of the thirteenth invention, in order to form the light-shield layer, the patterning in which the film laminated on the front substrate is exposed to light through the exposure mask for developing is performed on the photosensitive resin layer to remove the portions corresponding to the display image area on the front substrate. Hence, the light-shield layer can be easily and precisely formed.
To attain the aforementioned second object, a method of manufacturing a plasma display panel according to a fourteenth invention features in including a light-shield layer forming process for forming a light-shield layer on a portion of a dielectric layer opposing a portion situated between row electrode pairs and surrounded by bus electrodes, which is performed after the row electrodes each including transparent electrodes and the bus electrode are formed in pair on a front substrate to extend in a row direction and be arranged in a column direction, and then a dielectric layer is formed to overlay the row electrode pairs.
According to the method of manufacturing the plasma display panel of the fourteenth invention, the light-shield layer being black, dark-brown or the like in color absorbing light overlays the portion on the dielectric layer opposing the portion between the two back-to-back bus electrodes which will serve as the non-display line when images are formed. This allows the light-shield layer to absorb ambient light incident from the display surface of the front substrate directed toward the non-display image area, to prevent the reflection of the ambient light, resulting in the improvement in contrast on the screen. Further since the light-shield layer is formed on the dielectric layer, it is possible to increase the precision of the patterning upon formation and to further improve the contrast on the screen.
To attain the aforementioned second object, the method of manufacturing the plasma display panel according to a fifteenth invention features, in addition to the configuration of the fourteenth invention, in that the light-shield layer forming process comprises a lamination process for laminating a film including a black or dark color photosensitive resin layer on the dielectric layer, and a removal process for removing the film except for at least the portion corresponding to the portion surrounded by the bus electrodes and situated between the row electrode pairs, after the lamination process.
According to the method of manufacturing the plasma display panel of the fifteenth invention, the dielectric layer is formed on the front substrate on which the row electrode pairs have been formed, to overlay the row electrode pairs, and then the film including the black or dark-color photosensitive resin layer is laminated on the dielectric layer. After that, the light-shield layer to overlay the non-display image area is formed by a technique for removing the photosensitive resin layer except for portions corresponding to the non-display image area. Thus, the light-shield layer can be precisely formed.
To attain the aforementioned second object, a method of manufacturing a plasma display panel according to a sixteenth invention features an additional-dielectric layer forming process for forming an additional dielectric layer having a light-shield layer on a portion on a dielectric layer opposing two back-to-back arranged bus electrodes of adjacent row electrode pairs in a column direction and a portion surrounded by the two back-to-back bus electrodes, which is performed after the row electrodes each including transparent electrodes and the bus electrode are formed in pair on a front substrate to extend in a row direction and be arranged in a column direction, and then a dielectric layer is formed to overlay the row electrode pairs.
According to the method of manufacturing the plasma display panel of the sixteenth invention, the light-shield layer which is black, dark-brown or the like in color absorbing light forms at least the portion of the additional portion opposing each area between the two back-to-back bus electrodes which will serves as the non-display line at the time of formation of images. For this reason, the light-shield layer absorbs ambient light incident from the display surface of the front substrate directed toward the non-display image area not to permit the reflection of the ambient light, resulting in improvement in contrast on the screen. Further, the formation of the light-shield layer on the additional portion enhances the precision of the patterning upon formation of the light-shield layer, resulting in further improvement in contrast on the screen.
To attain the aforementioned second object, the method of manufacturing the plasma display panel according to a seventeenth invention features, in addition to the configuration of the sixteenth invention, in that the additional-dielectric layer forming process comprises a lamination process for laminating a film including a black or dark color photosensitive resin layer on the dielectric layer, and a removal process for removing the film except for the portion corresponding to the two back-to-back arranged bus electrodes of the adjacent row electrode pairs in column direction and the portion surrounded by the two back-to-back bus electrodes, after the lamination process.
According to the method of manufacturing the plasma display panel of the seventeenth invention, the dielectric layer is formed on the front substrate on which the row electrode pairs having been formed, to overlay the row electrode pairs. Then the film including the black or dark-color photosensitive resin layer is laminated on the dielectric layer. After that, the additional portion is formed by a technique for removing the film except for the portions corresponding to the additional portion. Thus, the additional portion configured by the light-shield layer can be smoothly formed.
To attain the aforementioned second object, the method of manufacturing the plasma display panel according to an eighteenth invention features, in addition to the configuration of the sixteenth invention, in that the additional-dielectric layer forming process comprises a lamination process for laminating a multi-layer film, including a black or dark color photosensitive resin layer and a transparent photosensitive resin layer, on the dielectric layer with the black or dark color photosensitive resin layer facing the dielectric layer, and a removal process for removing the film except for the portion corresponding to the two back-to-back bus electrodes of the adjacent row electrode pairs in the column direction and the portion surrounded by the two back-to-back bus electrodes, after the lamination process.
According to the method of manufacturing the plasma display panel of the eighteenth invention, the dielectric layer is formed on the front substrate on which the row electrode pairs having been formed, to overlay the row electrode pairs. Then the multi-layer film including the black or dark-color photosensitive resin layer and the transparent photosensitive resin layer is laminated on the dielectric layer. After that, the additional portion is formed by a technique for removing the film except for the portion corresponding to the additional portion. Thus, the additional portion including the light-shield layer can be smoothly formed. Moreover, when the additional portion is formed by the pattering in the photolithographic process in which the film is exposed to light through the exposure mask for developing, the transparent photosensitive resin layer of the film is set as the exposure face. This allows decrease of photosensitive characteristics during the exposing to be suppressed.
These and other objects and advantages of the present invention will become obvious to those skilled in the art upon review of the following description, the accompanying drawings and appended claims.